In general, spaying and neutering pets helps to reduce pet overpopulation problems. This decreases the number of unwanted pets tragically euthanized at shelters every year in our country. These surgeries also can prevent serious health problems such as uterine infection (pyometra), mammary cancer, testicular cancer, and some prostatic diseases. We generally recommend spay/neuter surgeries be performed at 6 months of age.
Responsible breeding of purebred animals is a very legitimate reason to forego spaying and neutering. If one of the above health-related problems occurs and cannot be managed, then spay/neuter should be performed.
There are good reasons to delay neutering larger-breed males until 12-14 months of age, if temperament and behavior allow it. Withdrawing testosterone influence earlier can delay growth-plate closure in the long bones, perhaps increasing the risk of some bone diseases.
Spay/neuter surgeries on exotic pets should be discussed on an individual basis.